Improved supervisord management is critical for maintenance of instances
between tests.

Since slapos.core 1.4.16+ slapos proxy is not able to consume or publish
non-strings, which makes tests not working.

They are dependencies of slapos.toolbox and we already agreed to put slapos.toolbox version in a shared file.

/cc @jerome @jm

/reviewed-on nexedi/slapos!502

Since some software releases have unit tests, it is good idea to run the
tests for each commit on slapos branch.

This SR follow slapos-testing SR in a way how tests are grouped and run.

Fixed erp5.util is used to expose good test suite names.